Daniel I. Rees (Author at Cato Institute)Individual Liberty, Free Markets, and Peacehttps://www.cato.org/
enamast@cato.org (Andrew Mast)webmaster@cato.org (Cato Webmaster)Thu, 31 Jan 2019 15:57:10 -0500Fri, 01 Feb 2019 08:18:56 -0500Public Health Efforts and the Decline in Urban Mortalityhttps://www.cato.org/publications/research-briefs-economic-policy/public-health-efforts-decline-urban-mortality
<p>Since the mid-19th century, mortality rates in the Western world
have plummeted and life expectancy has risen dramatically.
Sometimes referred to as “the mortality transition,”
this development is widely recognized as one of the most
significant in the history of human welfare. Two features
characterize the mortality transition. First, it was driven by
reductions in infectious diseases, and diseases of infancy and
childhood. Second, it was concentrated in urban areas: at the turn
of the 20th century, major cities were unsanitary havens of
pestilence; by 1940, urban mortality rates were comparable to those
of rural areas.</p>
<p>Traditionally, economists have attributed the mortality
transition to rising incomes, better nutrition, and the onset of
modern economic growth. More recent reviews of the literature
emphasize the role of public health efforts, especially those aimed
at purifying the water supply. For instance, David Cutler, Angus
Deaton, and Adriana Lleras-Muney argue that public health efforts
drove the dramatic reductions in food- and water-borne diseases at
the turn of the 20th century. Similarly, Dora Costa argues that
clean-water technologies such as filtration and chlorination were
“the biggest contributor[s] to the decline in infant
mortality,” but acknowledges that the effects of other public
health interventions “remain understudied.”</p>
<p>Using data on 25 major American cities for the years 1900-1940,
we revisit the causes of the urban mortality decline at the turn of
the 20th century. Specifically, we conduct a statistical
“horse race” that attempts to distinguish the effects
of ambitious (and often extraordinarily expensive) public health
interventions aimed at controlling mortality from food- and
water-borne diseases. Following previous researchers, we explore
the extent to which filtering and chlorinating drinking water
contributed to the decline in typhoid mortality observed during the
period under study and, more generally, to the observed declines in
total and infant mortality. In addition, we explore the effects of
several other municipal-level efforts that were, at the time,
viewed as critical in the fight against typhoid and other food- and
water-borne diseases, but have not received nearly as much
attention from modern-day researchers. These interventions include:
the treatment of sewage before its discharge into lakes, rivers,
and streams; projects designed to deliver clean water from further
afield, such as aqueducts and water cribs; requirements that milk
sold within city limits meet strict bacteriological standards; and
requirements that milk come from tuberculin-tested cows. Because
the urban mortality transition was characterized by substantial
reductions in infant and childhood mortality, and because exclusive
breastfeeding was not the norm during the period under study,
improvements in milk quality seem a particularly promising avenue
to explore.</p>
<p>Consistent with previous literature, we find that filtering the
municipal water supply sharply reduced typhoid mortality. In fact,
our results suggest that the building of a water filtration plant
cut the typhoid mortality rate by nearly 40 percent. More
generally, however, our results are not consistent with the
argument that public health interventions drove the extraordinary
reductions in infant and total mortality observed between 1900 and
1940. Specifically, we find that efforts to purify milk had no
appreciable effect on infant mortality and no effect on mortality
from non-pulmonary tuberculosis (TB), which was often transmitted
through infected milk. Likewise, neither chlorinating the water
supply nor constructing sewage treatment plants appears to have
been effective. Although water filtration is associated with a
(statistically insignificant) 1-3 percent decrease in total
mortality and an 11-13 percent decrease in infant mortality, these
estimates are considerably smaller than those found by previous
researchers, including David Cutler and Grant Miller, the authors
of the most influential study in this literature.</p>
<p>Because Cutler and Miller’s work is so influential, it is
important to document why our results are different from theirs.
Using their original data and specification, we find that the
estimated effect of filtration on total mortality shrinks by half
when we correct a handful of transcription errors and use US Bureau
of the Census population estimates to consistently calculate the
total mortality rate for the entire period under study, 1900-1936.
Correcting several errors in their infant mortality counts (79 of
410 infant mortality counts were incorrectly transcribed) reduces
the estimated Cutler and Miller effect of filtration on infant
mortality by two-thirds.</p>
<p>If public health interventions such as chlorination and
filtration cannot explain why mortality fell between 1900 and 1940,
what can? Our results point to other factors such as better living
conditions and improved nutrition as being responsible for the
sharp decline in urban mortality at the turn of the 20th century.
However, this is admittedly an educated guess. We hope that readers
will embrace the implicit challenge inherent in our results and
redouble their efforts to discover the true causes of the urban
mortality transition.</p>
<p><strong>NOTE:</strong><br>
This research brief is based on D. Mark Anderson, Kerwin Kofi
Charles, and Daniel I. Rees, “Public Health Efforts and the
Decline in Urban Mortality,” NBER Working Paper no. 25027,
September 2018, <a href="http://www.nber.org/papers/w25027" target=
"_blank">http://www.nber.org/papers/w25027</a>.</p>
https://www.cato.org/publications/research-briefs-economic-policy/public-health-efforts-decline-urban-mortalityWed, 13 Feb 2019 (All day)Daniel I. Rees (Author at Cato Institute)D. Mark Anderson, Kerwin Kofi Charles, Daniel I. Rees